Hydraulic lifting jack



Nov. 5, 1929. J. E. LUDWIG 1,734,816

HYDRAULIC LIFTING JACK Filed Sept. 22, 1925 Il 'M114 r11 11171111111111111111 i: :111

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Patented Nov. 5, 1929 UNITED STATES ori-ics 'A JAMES E. LUDWIG, 0F PORT HURON, MICHIGAN HYDRAULIC LIFTING TACK Application led September 22, 1925. Serial No. 57,837.

`in different adjusted positions within the other part, so as to render the lifting piston rod extensible.

Another purpose is to provide a lifting jack wherein a gear pump is employed for forcing the lifting fluid under the piston.l and after the piston is raised, to keep the fluid circulating, there being means to hold the lifting piston rod in a lifted position so as to stop the action of the pump.

Still another purpose is the provision of a hydraulic pump of the gear type including means for withdrawing the lifting fluid from under the piston and conveying it back into the tank, so as to allow the lifting piston rod to descend to its normal position provided the holding means for the lifting piston rod is removed.

It is to be understood that the particulars herein given are in no way limitative and that, while still keeping within the scope of the invention, any desired modifications of detail and desired proportions may be made in the apparatus according to the circumstances.

Tlie invention comprises further features and combinations of parts to be hereinafter set forth, shown in the drawings and claimed.

In the drawings:

Figure 1 is a vertical sectional view through the improved hydraulic lifting pump, showing the lifting piston rod and the piston in its normal lowered position. t

Figure 2 is a vertical sectional view through the lifting jack proper, showing the liftin piston rod in a raised position.

Re erring to the drawings, l designates a cylinder provided at its upper end with a substantial circular flange 2. The flange is in the form of a plate with a central opening 3 which has an annular collar 4. The opening 3 is threaded to threadingly engage with the upper end of the cylinder 1. rilhe flange 2 may be bolted at 5 to the under surface of the flooring of a building so as to support the cylinder in a' depending position below the flooring.

The floorings cut away or provided with A an opening 6 for the reception of a radius arm 7 which is carried by the lifting piston rod 8. The radius arm carries folding safety lugs 9 which, when extended, may engage on opposite sides of an ob'ect to be lifted or under an object, there y preventing displacement thereof during the act of being lifted. The lifting piston rod is telescopically mounted in thecylinder 1 and consists of two sections, an outer tubular section 10 and an inner rod section 11, the latter .being telescopically mounted within the former whh is closed at its lower end, as indicated at l A piston 13 is mounted for movement in the cylinder 1 and is provided with suitable packing 14 to prevent the escape of the lifting fluid to a point above the piston. A

-threaded rod 15 passes through the piston and has a head 16 on one end thereof to retain the upper packing on the piston, there being a member or nut 17 threadin ly engaged with the lower end of the rod 15 to hold the lower packing in position. Suitable plates 18 are interposed between the head and the nut 17 to insure clamping the packing in position. The inner and outer sections of the lifting piston rod are rovided with transversely disposed openings or apertures 19 and 20 which register when the two sections are in normal lowered positions, so as to receive a pin 21 to hold the lifting piston rod in a raised position. j

It is obvious that vthe inner section of the lifting piston rod may, as in Figure 2, be telescopically raised manually, so that the radius arm 7 may engage under an object to be lifted which stands a considerable distance from the surface of the floor, that is` to say, before the outer section 10 of said rod is actuated by the hydraulically moved piston 13. However, it may be noted that the lifting piston rod' may be actuated h draulically without rst having lifted t e inner section of the lifting piston rod, so that the radius arm 7 may engage under an object to be lifted which elther rests directly upon the ioor or a very short distance above the surface of the floor.

When the inner section 11 is raised manually for the purpose ofl permitting the arm 1o 7 to engage under an object which stands a Substantial distance above the surface of the floor, a pin 22 may engage through certain of the openings or apertures 19, the pin resting upon the upper end ofthe section 10 of 15 the lifting piston rod so that the section 11 may be held in a raised position with respect to ,the section 10. The section 11 may be moved telescopically substantially half the f distance of the section 10,.in which case the 120 pin 22 may pass through certain ofthe registering openings or apertures 19 and 20. By 'this arrangement, the lifting piston rod is rendered extensible for lifting objects which stand at different heights from the surface 35 of the floor. Q

A gear pump 23 is provided which comprises a casin 24 with interior passages 25 and 26 and 2% and 28. Thev passage 27 is positioned substantially centrally'of the cas- '30 ing of the pump, whereas the passage 28 is formed through the pump to the right of the center of the pum and communicates at 29 vwith a pipe 30 lea ing from a tank 31. This tank contains a lifting Huid for the purpose vof iniparting a lifting action to the lifting piston rod. Midway of the passage 27 are intermeshing gears 32 and 33, of which only one, for instance the gear 32, may be manually or automatically actuated, thereby imparting teeth of these gears are substantially in the center o'f the passage 27, so as to feed the lifting fiuid through the pump.

j A pipe 34 communicates with the assages 25 and 26 and is in turn connected to t e lower end of the cylinder 1 at a point to supply the lifting iuid under the piston. A pipe 35 is threaded into the casing of the pum 'and communicates with the passage 28 which in turn, as previously stated, communicates with the pipe 30 which leads to the tank. The ipe 35 isfin turn connected to the cylin er 1 in order to communicate withv the interior thereof, there being a check valve 36 located at the point of connection of the pipe 35 with the cylinder 1, thereby preventing a backow of the liquid iuid into the cylinder. I A'two-way valve 37 is located where the 'two passages 25 and 26 communicate with the pipe 30 while a second two-way valve 38 is A positioned at the junction where the pipe 34 communicates with the passages 25 and 26. AWhen it is the purpose to impart movement to the lifting piston rod, the system of the ing movement to the other. The intermesh- P pump being filled with a lifting Huid, the two-way valve 38 is set so as to communicate the pipe' 34l with the passages 27 and 26 and the two-way valve 37 communicating the pipe 30 and the passage 27, rotating movement may be imparted tothe gear 32,in which case the gears, at the point of their intermeshing, will impart movement to the lifting fluid and force it into the cylinder 1 under the piston. The piston will then rise to a position above where the pipe 35 communicates with the cylinder 1. The lifting iuid will then circulate through the system of the pump, that is to say, Will travel back through the pump by way of the pipe 35 and the passage 28 through the pipe 30 to the tank.

After the piston has been elevated to a position just above the communication of the pipe 35 with the cylinder 1, the pin- 21 may be inserted through the lifting piston rod to hold the same in such supported position, as shown in Fqigure 2. The check valve 36 acts to prevent the lifting Huid from flowing into the cylinder 1 from the pipe 35. After the lift- Y ing piston rod has been raised and it is supported by the pin 21, the two-way valves 37 and 38 may be adjusted so as to communicate the passage 26 with the pipe 3() and communicate the pipe 34 with the passage 25, thereby closing communication between the pipe 30 and the passage 25 and also closin communication between the passage 26 an the pipe 34. In this event, thefluld will be withdrawn from the cylinder 1 by way of the pipe 34 through the passage 25, down through the passage 27, then through the passage 26 and up through the pipe 30, the gears 32 and 33 rotating in the same direction .as when feeding iiuid from the tank through the assage 27 and through the pipe 34. W'hen the lifting fluid is being withdrawn from the cylinder 1, the pin 21 has been previously removed, allowing the lifting piston rod to gradually descend.

The invent-ion having been set forth, what is claimed is:

v A jack of the kind described comprising a cylinder, a member slidably mounted in the cylinder, a tank, a pump, a casing in which said pump is inclosed and formed interiorly with a plurality of passages of which one is in constant communication with the tank and with the cylinder adjacent the upper end and the other is in valved communication with the tank and with the cylinder at the lower end, and three-way valves for alternately and selectively placing either of said passages in s communication w1th the pump.

In testimony whereof he aiixes his signa- 

